Hitherto, this type of chip-like solid electrolyte capacitor has been formed by preparing a capacitor element formed by sequentially depositing a layer of semiconductor metal oxide such as manganese dioxide and a cathode layer made of carbon silver paint, on an anode which is a sintered body of a valve metal such as tantalum having an anode lead-out line, which is made of a valve metal such as tantalum, and also having a surface thereof provided with a dielectric oxidizing film, and then encapsulating this capacitor element in an electrically insulative resin. From this capacitor body extend an anode terminal, connected to the anode lead-out line, and a cathode terminal connected to the cathode layer.
Representative examples of conventional chip-like solid electrolyte capacitors are shown in FIGS. 1(a) and 1(b) and FIGS. 2(a) and 2(b). In FIGS. 1(a) and 1(b) is shown a capacitor element 1 mold-encapsulated in an insulative resin 2 to provide a capacitor body 3 and having a solderable anode terminal 4 connected by welding to an anode lead-out line 1a of the capacitor element 1 and a solderable cathode terminal 5 connected by soldering to an anode layer in the outer shell of the capacitor element 1. The terminals extend outwards from the bottom face of the capacitor body 3. In FIGS. 2(a) and (b) is shown a capacitor body with the anode terminal 4 and the cathode terminal 5 extending outwards from the opposite end faces of the capacitor body 3 and then bent so as to extend along the end face and bottom face.
When such a chip-like solid electrolyte capacitor is to be manufactured, manufacturing is carried out by steps such as shown in FIG. 3. FIG. 3 illustrates manufacturing steps for the manufacture of the chip-like solid electrolyte capacitor shown in FIGS. 1(a) and (b) and is a method which comprises perforating a lead frame 6 to provide two tongues 4' and 5' such as at step A, subsequently bending the tongues 4' and 5' to form the anode and cathode terminals 4 and 5 such as at step B, placing the capacitor element 1 on the anode and cathode terminals 4 and 5 such as at step C, connecting the anode lead-out line 1a and the cathode layer in the outer shell of the capacitor element 1 with the anode terminal 4 and the cathode terminal 5 such as at step D and simultaneously cutting the anode lead-out line 1a adjacent the capacitor element 1, mold-encapsulating the capacitor element 1, including portions of the anode and cathode terminals 4 and 5, with insulative resin 2 such as at step E, and separating the anode and cathode terminals 4 and 5 from the lead frame 6. It is to be noted that the capacitor element 1 is positioned on the lead frame 6 with the anode lead-out line 1a fixed by welding to a retainer plate 7.
However, in such a conventional chip-like solid electrolyte capacitor, in the construction as shown in FIGS. 1(a) and (b), there is a disadvantage in that both terminals of the anode and cathode terminals 4 and 5 extend outwardly from the capacitor body 3 and the overall dimensions are large and, also, it is not possible to apply the capacitor body to a substrate by a method other than a so-called reflow-soldering method wherein, after placing the capacitor body on a printed substrate, excess solder which has been attached by heating the printed substrate, is re-fused to effect the soldering. On the other hand, in the construction shown in FIGS. 2(a) and (b), since the anode and cathode terminals 4 and 5 are bent so as to extend along the end and bottom faces of the capacitor body 3, the overall size is small, but since the surface areas of the anode and cathode terminals 4 and 5 exposed to the end face of the capacitor body 3 are still small and the widths of these terminals are far smaller than the width of the capacitor body 3, incorporation onto the printed substrate can, as is the case with the former, only be effected by the reflow-soldering method.
Moreover, as is clear from the manufacturing method shown in FIG. 3, the positioning of the anode and cathode terminals 4 and 5 of the capacitor body 3 is not carried out with any great precision and, therefore, the positions at which the anode terminal 4 and the cathode terminal 5 are connected vary resulting in such a disadvantage that the quality of the capacitor bodies vary from one to another.
In order to obviate these problems, the inventors developed a chip-like solid electrolyte capacitor such as shown in FIG. 4.
In FIG. 4, an anode terminal 8 is connected by a weld 9 to an anode lead-out line 1a of the capacitor element 1, and a cathode terminal 10 is provided which has a U-shaped fixing portion 10a, a neck portion 10b, a vertical portion 10c and an external connection portion 10d. 11 designates a soldering area. The fixing and neck portions 10a and 10b of the cathode terminal 10 are fixed by soldering in the soldering area 11 to the cathode layer in the outer shell of the capacitor element 1 in a position above the capacitor element 1 while to the vertical portion 10c having first and second bent portions 10e and 10f bent at right angles to the neck portion 10b and having a width smaller than the fixing portion 10a is integrally continuously connected the U-shaped external connection portion 10d opening in a direction towards the capacitor element 1.
In the capacitor having such a construction, although it is ideal to make the anode terminal face and the horizontal plane of the cathode terminal flush with each other after the soldering of the cathode terminal 10 to the capacitor element 1 and the welding of the anode terminal 8 to the anode lead-out line 1a, since the shape of the cathode terminal 10 is complicated as can be seen from FIG. 4, the dimensions of the cathode terminal 10 tend to deviate considerably and, in the event that upper and lower molds are clamped together after the insertion of the capacitor during the transfer molding process, the horizontal planes of the anode terminal face and the cathode terminal face are displaced and, therefore, not only is an excessive mechanical stress imposed on the capacitor element 1, but also the mechanical stress imposed on the capacitor element 1 is further increased by the effect of the pressure applied to the capacitor element 1 during the injection of resin into a space formed between the upper and lower molds, resulting in deterioration of the capacitor element 1. In addition, since the hardening of the resin takes place at a high temperature of 130.degree. C. to 200.degree. C., the anode and cathode terminals 8 and 10 are caused to expand due to the high temperature and a mechanical stress separate from said mechanical stress is imposed on the capacitor element 1, thereby causing the problem that the capacitor element 1 is caused to deteriorate.